Rasterizing a clipped image/group of objects results in extra white space in the resulting image.
If I rasterize a clipped image, the result is the same size as the clipped image but with extra whitespace surrounding the clipping boundaries. Expected result, IMO, should be that the resulting image is only as large as the clipping object.
Illustrator now crops clipping groups to their masks’ boundaries, the excesses get trimmed, no extra empty areas get kept.
Katey J Ward commented
When I crop an image in Illustrator, the image turns out to have a white line across it after I apply the crop feature
It sounds like you want a crop tool added for raster and vector objects. What you are suggesting would not technically be a clipping mask anymore as the elements that are being clipped would be deleted which is not the purpose of a clipping mask.
For a workaround if this is a vector object you can use pathfinder - trim to essentially crop the object and then rasterize. If it's a raster image you will need to crop it in photoshop although there are plugins by astute that do what you are asking.
When selecting an image within a clipping mask with the direct selection tool (white pointer), and rasterizing the selection, the entire clipped group gets rasterized.